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Hutchinson K, van Zandwijk JP, Vester MEM, Seth A, Bilo RAC, van Rijn RR, Loeve AJ. Modeling of inflicted head injury by shaking trauma in children: what can we learn? : Update to parts I&II: A systematic review of animal, mathematical and physical models. Forensic Sci Med Pathol 2024:10.1007/s12024-023-00765-5. [PMID: 38236351 DOI: 10.1007/s12024-023-00765-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2023] [Indexed: 01/19/2024]
Abstract
Inflicted shaking trauma can cause injury in infants, but exact injury mechanisms remain unclear. Controversy exists, particularly in courts, whether additional causes such as impact are required to produce injuries found in cases of (suspected) shaking. Publication rates of studies on animal and biomechanical models of inflicted head injury by shaking trauma (IHI-ST) in infants continue rising. Dissention on the topic, combined with its legal relevance, makes maintaining an up-to-date, clear and accessible overview of the current knowledge-base on IHI-ST essential. The current work reviews recent (2017-2023) studies using models of IHI-ST, serving as an update to two previously published reviews. A systematic review was conducted in Scopus and PubMed for articles using animal, physical and mathematical models for IHI-ST. Using the PRISMA methodology, two researchers independently screened the publications. Two, five, and ten publications were included on animal, physical, and mathematical models of IHI-ST, respectively. Both animal model studies used rodents. It is unknown to what degree these can accurately represent IHI-ST. Physical models were used mostly to investigate gross head-kinematics during shaking. Most mathematical models were used to study local effects on the eye and the head's internal structures. All injury thresholds and material properties used were based on scaled adult or animal data. Shaking motions used as inputs for animal, physical and mathematical models were mostly greatly simplified. Future research should focus on using more accurate shaking inputs for models, and on developing or and validating accurate injury thresholds applicable for shaking.
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Affiliation(s)
- Kim Hutchinson
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime & Materials Engineering, Delft University of Technology, Mekelweg 2, 2628, Delft, CD, Netherlands
| | - Jan Peter van Zandwijk
- Division of Digital and Biometric Traces, Netherlands Forensic Institute, Laan Van Ypenburg 6, 2497, The Hague, GB, Netherlands
| | - Marloes E M Vester
- Care Needs Assessment Centre CIZ, Orteliuslaan 1000, 3500 GR, Utrecht, Netherlands
| | - Ajay Seth
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime & Materials Engineering, Delft University of Technology, Mekelweg 2, 2628, Delft, CD, Netherlands
| | - Rob A C Bilo
- Veilig Thuis Rotterdam Rijnmond (Center for the Reporting of Child Abuse, Domestic Violence and Elder Abuse), Paul Krugerstraat 181, 3072 GJ, Rotterdam, Netherlands
| | - Rick R van Rijn
- Department of Radiology and Nuclear Medicine, Academic Medical Center Amsterdam, Meibergdreef 9, 1105AZ, Amsterdam, Netherlands
- Department of Forensic Medicine, Netherlands Forensic Institute, Laan Van Ypenburg 6, 2497, The Hague, GB, Netherlands
| | - Arjo J Loeve
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime & Materials Engineering, Delft University of Technology, Mekelweg 2, 2628, Delft, CD, Netherlands.
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2
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Age effects on the mechanical behavior of human cerebral bridging veins. Clin Biomech (Bristol, Avon) 2022; 100:105792. [PMID: 36327547 DOI: 10.1016/j.clinbiomech.2022.105792] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/26/2022] [Accepted: 10/02/2022] [Indexed: 02/07/2023]
Abstract
BACKGROUND It is well established that the probability of occurrence of acute subdural hematomas in traumatic situations increases with age, since the main cause of such hematomas is the mechanical failure of cerebral blood vessels known as bridging veins. This research aims to determine whether there is an effect of age on the mechanical properties of these cerebral vessels, because previous reported studies were conflicting. METHODS This study used mechanical tests blue of cerebral bridging veins from post-mortem human subjects. In particular, a series of in vitro tensile tests were performed on a balanced sample of bridging veins from different human subjects. FINDINGS The mechanical parameters measured from the tests were analyzed by means of regression analysis looking for age related effects. The results show that there is a significant effect on both the ultimate strength, maximum stress and strain that the specimens can withstand. The quantitative analysis shows reductions of nearly 50% in ultimate stress, and almost 35% in ultimate strain. INTERPRETATION Mechanical deterioration of the mechanical strength of cerebral blood vessels seems to be a major factor involved in the increase of frequency of acute subdural hematoma in elderly people in a wide range of life-threatening traumatic situations.
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Injury Metrics for Assessing the Risk of Acute Subdural Hematoma in Traumatic Events. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182413296. [PMID: 34948905 PMCID: PMC8702226 DOI: 10.3390/ijerph182413296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 11/17/2022]
Abstract
Worldwide, the ocurrence of acute subdural hematomas (ASDHs) in road traffic crashes is a major public health problem. ASDHs are usually produced by loss of structural integrity of one of the cerebral bridging veins (CBVs) linking the parasagittal sinus to the brain. Therefore, to assess the risk of ASDH it is important to know the mechanical conditions to which the CBVs are subjected during a potentially traumatic event (such as a traffic accident or a fall from height). Recently, new studies on CBVs have been published allowing much more accurate prediction of the likelihood of mechanical failure of CBVs. These new data can be used to propose new damage metrics, which make more accurate predictions about the probability of occurrence of ASDH in road crashes. This would allow a better assessement of the effects of passive safety countermeasures and, consequently, to improve vehicle restraint systems. Currently, some widely used damage metrics are based on partially obsolete data and measurements of the mechanical behavior of CBVs that have not been confirmed by subsequent studies. This paper proposes a revision of some existing metrics and constructs a new metric based on more accurate recent data on the mechanical failure of human CBVs.
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García-Vilana S, Sánchez-Molina D, Llumà J, Galtés I, Velázquez-Ameijide J, Rebollo-Soria MC, Arregui-Dalmases C. Viscoelastic Characterization of Parasagittal Bridging Veins and Implications for Traumatic Brain Injury: A Pilot Study. Bioengineering (Basel) 2021; 8:145. [PMID: 34677218 PMCID: PMC8533420 DOI: 10.3390/bioengineering8100145] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/05/2021] [Accepted: 10/12/2021] [Indexed: 01/29/2023] Open
Abstract
Many previous studies on the mechanical properties of Parasagittal Bridging Veins (PSBVs) found that strain rate had a significant effect on some mechanical properties, but did not extensively study the viscoelastic effects, which are difficult to detect with uniaxial simple tensile tests. In this study, relaxation tests and tests under cyclic loading were performed, and it was found that PSBVs do indeed exhibit clear viscoelastic effects. In addition, a complete viscoelastic model for the PSBVs is proposed and data from relaxation, cyclic load and load-unload tests for triangular loads are used to find reference values that characterize the viscoelastic behavior of the PSBVs. Although such models have been proposed for other types of blood vessels, this is the first study that clearly demonstrates the existence of viscoelastic effects from an experimental point of view and also proposes a specific model to explain the data obtained. Finally, this study provides reference values for the usual viscoelastic properties, which would allow more accurate numerical simulation of PSBVs by means of computational models.
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Affiliation(s)
- Silvia García-Vilana
- Escola d'Enginyeria de Barcelona Est, Universitat Politècnica de Catalunya, Av. Eduard Maristany, 16, 08019 Barcelona, Spain
| | - David Sánchez-Molina
- Escola d'Enginyeria de Barcelona Est, Universitat Politècnica de Catalunya, Av. Eduard Maristany, 16, 08019 Barcelona, Spain
| | - Jordi Llumà
- Escola d'Enginyeria de Barcelona Est, Universitat Politècnica de Catalunya, Av. Eduard Maristany, 16, 08019 Barcelona, Spain
| | - Ignasi Galtés
- Institut de Medicina Legal i Ciències Forenses de Catalunya, G.V. Corts Catalanes, 111, 08014 Barcelona, Spain
- Departament de Psiquiatria i de Medicina Legal, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193 Barcelona, Spain
| | - Juan Velázquez-Ameijide
- Escola d'Enginyeria de Barcelona Est, Universitat Politècnica de Catalunya, Av. Eduard Maristany, 16, 08019 Barcelona, Spain
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Stray-Pedersen A, Strisland F, Rognum TO, Schiks LAH, Loeve AJ. Violent Infant Surrogate Shaking: Continuous High-Magnitude Centripetal Force and Abrupt Shift in Tangential Acceleration May Explain High Risk of Subdural Hemorrhage. Neurotrauma Rep 2021; 2:224-231. [PMID: 34223553 PMCID: PMC8240836 DOI: 10.1089/neur.2021.0013] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Violent shaking is believed to be a common mechanism of injury in pediatric abusive head trauma. Typical intracranial injuries include subdural and retinal hemorrhages. Using a laboratory surrogate model we conducted experiments evaluating the head motion patterns that may occur in violent shaking. An anthropomorphic test device (ATD; Q0 dummy) matching an infant of 3.5 kg was assembled. The head interior was equipped with accelerometers enabling assessment of three-axial accelerations. Fifteen volunteers were asked to shake the surrogate vigorously holding a firm grip around the torso. We observed the volunteers performing manual shaking of the surrogate at a median duration of 15.5 sec (range 5-54 sec). Typical acceleration/deceleration patterns were produced after 2-3 shakes with a steady-state shaking motion at a pace of 4-6 cycles (back and forth) per second. Mean peak sagittal tangential accelerations at the vertex were 45.7g (range 14.2-105.1g). The acceleration component in the orthogonal direction, the radial acceleration, fluctuated around a negative mean of more than 4g showing that the surrogate head was continuously subjected to centripetal forces caused by rotations. This surrogate experiment showed that violent shaking may induce high peak tangential accelerations and concomitantly a continuous high-magnitude centripetal force. We hypothesize that the latter component may cause increased pressure in the subdural compartment in the cranial roof and may cause constant compression of the brain and possibly increased stretching or shearing of the bridging veins. This may contribute to the mechanism accountable for subdural hematoma in abusive head trauma.
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Affiliation(s)
- Arne Stray-Pedersen
- Department of Forensic Sciences, Division of Laboratory Medicine, Oslo University Hospital, Nydalen, Oslo, Norway.,Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Blindern, Oslo, Norway
| | | | - Torleiv Ole Rognum
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Blindern, Oslo, Norway
| | - Luuk Antoon Hubertus Schiks
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
| | - Arjo Jozef Loeve
- Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands.,Co van Ledden Hulsebosch Center of Forensic Science and Medicine, Amsterdam, The Netherlands
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Walsh DR, Lynch JJ, O' Connor DT, Newport DT, Mulvihill JJE. Mechanical and structural characterisation of the dural venous sinuses. Sci Rep 2020; 10:21763. [PMID: 33303894 PMCID: PMC7729903 DOI: 10.1038/s41598-020-78694-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 11/26/2020] [Indexed: 12/27/2022] Open
Abstract
The dural venous sinuses play an integral role in draining venous blood from the cranial cavity. As a result of the sinuses anatomical location, they are of significant importance when evaluating the mechanopathology of traumatic brain injury (TBI). Despite the importance of the dural venous sinuses in normal neurophysiology, no mechanical analyses have been conducted on the tissues. In this study, we conduct mechanical and structural analysis on porcine dural venous sinus tissue to help elucidate the tissues’ function in healthy and diseased conditions. With longitudinal elastic moduli values ranging from 33 to 58 MPa, we demonstrate that the sinuses exhibit higher mechanical stiffness than that of native dural tissue, which may be of interest to the field of TBI modelling. Furthermore, by employing histological staining and a colour deconvolution protocol, we show that the sinuses have a collagen-dominant extracellular matrix, with collagen area fractions ranging from 84 to 94%, which likely explains the tissue’s large mechanical stiffness. In summary, we provide the first investigation of the dural venous sinus mechanical behaviour with accompanying structural analysis, which may aid in understanding TBI mechanopathology.
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Affiliation(s)
- Darragh R Walsh
- Bernal Institute, University of Limerick, Limerick, Ireland.,School of Engineering, University of Limerick, Limerick, Ireland
| | - James J Lynch
- Bernal Institute, University of Limerick, Limerick, Ireland.,School of Engineering, University of Limerick, Limerick, Ireland
| | - David T O' Connor
- Bernal Institute, University of Limerick, Limerick, Ireland.,School of Engineering, University of Limerick, Limerick, Ireland.,Health Research Institute, University of Limerick, Limerick, Ireland
| | - David T Newport
- Bernal Institute, University of Limerick, Limerick, Ireland.,School of Engineering, University of Limerick, Limerick, Ireland
| | - John J E Mulvihill
- Bernal Institute, University of Limerick, Limerick, Ireland. .,School of Engineering, University of Limerick, Limerick, Ireland. .,Health Research Institute, University of Limerick, Limerick, Ireland.
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7
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Pasquesi SA, Seidi M, Hajiaghamemar M, Margulies SS. Predictions of neonatal porcine bridging vein rupture and extra-axial hemorrhage during rapid head rotations. J Mech Behav Biomed Mater 2020; 106:103740. [PMID: 32250951 DOI: 10.1016/j.jmbbm.2020.103740] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 02/07/2020] [Accepted: 02/26/2020] [Indexed: 11/17/2022]
Abstract
When the head is rotated rapidly, the movement of the brain lags that of the skull. Intracranial contents between the brain and skull include meninges, cerebrospinal fluid (CSF), and cerebral vasculature. Among the cerebral vasculature in this space are the parasagittal bridging veins (BVs), which drain blood from the brain into the superior sagittal sinus (SSS), which is housed within the falx cerebri, adhered to the inner surface of the skull. Differential motion between the brain and skull that may occur during a traumatic event is thought to stretch BVs, causing damage and producing extra-axial hemorrhage (EAH). Finite element (FE) modeling is a technique often used to aid in the understanding and prediction of traumatic brain injury (TBI), and estimation of tissue deformation during traumatic events provides insight into kinematic injury thresholds. Using a FE model of the newborn porcine head with neonatal porcine brain and BV properties, single and cyclic rapid head rotations without impact were simulated. Measured BV failure properties were used to predict BV rupture. By comparing simulation outputs to observations of EAH in a development group of in vivo studies of rapid non-impact head rotations in the piglet, it was determined that failure of 16.7% of BV elements was associated with a 50% risk of EAH, and showed in a separate validation group that this threshold predicted the occurrence of EAH with 100% sensitivity and 100% specificity for single rapid non-impact rotations. This threshold for failed BV elements performed with 90% overall correct prediction in simulations of cyclic rotational head injuries. A 50% risk of EAH was associated with head angular velocities of 94.74 rad/s and angular accelerations of 29.60 krad/s2 in the newborn piglet. Future studies may build on these findings for BV failure in the piglet to develop predictive models for BV failure in human infants.
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Affiliation(s)
| | - Morteza Seidi
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, USA
| | - Marzieh Hajiaghamemar
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, USA
| | - Susan S Margulies
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, USA.
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Paritala PK, Yarlagadda PKDV, Kansky R, Wang J, Mendieta JB, Gu Y, McGahan T, Lloyd T, Li Z. Stress-Relaxation and Cyclic Behavior of Human Carotid Plaque Tissue. Front Bioeng Biotechnol 2020; 8:60. [PMID: 32117939 PMCID: PMC7026010 DOI: 10.3389/fbioe.2020.00060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/23/2020] [Indexed: 12/12/2022] Open
Abstract
Atherosclerotic plaque rupture is a catastrophic event that contributes to mortality and long-term disability. A better understanding of the plaque mechanical behavior is essential for the identification of vulnerable plaques pre-rupture. Plaque is subjected to a natural dynamic mechanical environment under hemodynamic loading. Therefore, it is important to understand the mechanical response of plaque tissue under cyclic loading conditions. Moreover, experimental data of such mechanical properties are fundamental for more clinically relevant biomechanical modeling and numerical simulations for risk stratification. This study aims to experimentally and numerically characterize the stress-relaxation and cyclic mechanical behavior of carotid plaque tissue. Instron microtester equipped with a custom-developed setup was used for the experiments. Carotid plaque samples excised at endarterectomy were subjected to uniaxial tensile, stress-relaxation, and cyclic loading protocols. Thirty percent of the underlying load level obtained from the uniaxial tensile test results was used to determine the change in mechanical properties of the tissue over time under a controlled testing environment (Control tests). The stress-relaxation test data was used to calibrate the hyperelastic (neo-Hookean, Ogden, Yeoh) and linear viscoelastic (Prony series) material parameters. The normalized relaxation force increased initially and slowly stabilized toward the end of relaxation phase, highlighting the viscoelastic behavior. During the cyclic tests, there was a decrease in the peak force as a function of the cycle number indicating mechanical distension due to repeated loading that varied with different frequencies. The material also accumulated residual deformation, which increased with the cycle number. This trend showed softening behavior of the samples. The results of this preliminary study provide an enhanced understanding of in vivo stress-relaxation and cyclic behavior of the human atherosclerotic plaque tissue.
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Affiliation(s)
- Phani Kumari Paritala
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
| | - Prasad K D V Yarlagadda
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
| | - Rhys Kansky
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
| | - Jiaqiu Wang
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
| | - Jessica Benitez Mendieta
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
| | - YuanTong Gu
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
| | - Tim McGahan
- Department of Vascular Surgery, Princess Alexandra Hospital, Brisbane, QLD, Australia
| | - Thomas Lloyd
- Department of Radiology, Princess Alexandra Hospital, Brisbane, QLD, Australia
| | - Zhiyong Li
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD, Australia
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Thresholds for the assessment of inflicted head injury by shaking trauma in infants: a systematic review. Forensic Sci Int 2019; 306:110060. [PMID: 31785511 DOI: 10.1016/j.forsciint.2019.110060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 11/11/2019] [Accepted: 11/13/2019] [Indexed: 12/14/2022]
Abstract
In order to investigate potential causal relations between the shaking of infants and injuries, biomechanical studies compare brain and skull dynamic behavior during shaking to injury thresholds. However, performing shaking tolerance research on infants, either in vivo or ex vivo, is extremely difficult, if not impossible. Therefore, infant injury thresholds are usually estimated by scaling or extrapolating adult or animal data obtained from crash tests or whiplash experiments. However, it is doubtful whether such data accurately matches the biomechanics of shaking in an infant. Hence some thresholds may be inappropriate to be used for the assessment of inflicted head injury by shaking trauma in infants. A systematic literature review was conducted to 1) provide an overview of existing thresholds for head- and neck injuries related to violent shaking, and 2) to identify and discuss which thresholds have been used or could be used for the assessment of inflicted head injury by shaking trauma in infants. Key findings: The majority of studies establishing or proposing injury thresholds were found to be based on loading cycle durations and loading cycle repetitions that did not resemble those occurring during shaking, or had experimental conditions that were insufficiently documented in order to evaluate the applicability of such thresholds. Injury thresholds that were applied in studies aimed at assessing whether an injury could occur under certain shaking conditions were all based on experiments that did not properly replicate the loading characteristics of shaking. Somewhat validated threshold scaling methods only exist for scaling concussive injury thresholds from adult primate to adult human. Scaling methods that have been used for scaling other injuries, or for scaling adult injury thresholds to infants were not validated. There is a clear and urgent need for new injury thresholds established by accurately replicating the loading characteristics of shaking.
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Li Z, Wang G, Ji C, Jiang J, Wang J, Wang J. Characterization of the mechanical properties for cranial bones of 8-week-old piglets: the effect of strain rate and region. Biomech Model Mechanobiol 2019; 18:1697-1707. [DOI: 10.1007/s10237-019-01169-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 05/12/2019] [Indexed: 11/25/2022]
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Walsh DR, Ross AM, Malijauskaite S, Flanagan BD, Newport DT, McGourty KD, Mulvihill JJ. Regional mechanical and biochemical properties of the porcine cortical meninges. Acta Biomater 2018; 80:237-246. [PMID: 30208332 DOI: 10.1016/j.actbio.2018.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 08/05/2018] [Accepted: 09/05/2018] [Indexed: 01/14/2023]
Abstract
The meninges are pivotal in protecting the brain against traumatic brain injury (TBI), an ongoing issue in most mainstream sports. Improved understanding of TBI biomechanics and pathophysiology is desirable to improve preventative measures, such as protective helmets, and advance our TBI diagnostic/prognostic capabilities. This study mechanically characterised the porcine meninges by performing uniaxial tensile testing on the dura mater (DM) tissue adjacent to the frontal, parietal, temporal, and occipital lobes of the cerebellum and superior sagittal sinus region of the DM. Mechanical characterisation revealed a significantly higher elastic modulus for the superior sagittal sinus region when compared to other regions in the DM. The superior sagittal sinus and parietal regions of the DM also displayed local mechanical anisotropy. Further, fatigue was noted in the DM following ten preconditioning cycles, which could have important implications in the context of repetitive TBI. To further understand differences in regional mechanical properties, regional variations in protein content (collagen I, collagen III, fibronectin and elastin) were examined by immunoblot analysis. The superior sagittal sinus was found to have significantly higher collagen I, elastin, and fibronectin content. The frontal region was also identified to have significantly higher collagen I and fibronectin content while the temporal region had increased elastin and fibronectin content. Regional differences in the mechanical and biochemical properties along with regional tissue thickness differences within the DM reveal that the tissue is a non-homogeneous structure. In particular, the potentially influential role of the superior sagittal sinus in TBI biomechanics warrants further investigation. STATEMENT OF SIGNIFICANCE: This study addresses the lack of regional mechanical analysis of the cortical meninges, particularly the dura mater (DM), with accompanying biochemical analysis. To mechanically characterise the stiffness of the DM by region, uniaxial tensile testing was carried out on the DM tissue adjacent to the frontal, parietal, temporal and occipital lobes along with the DM tissue associated with the superior sagittal sinus. To the best of the authors' knowledge, the work presented here identifies, for the first time, the heterogeneous nature of the DM's mechanical stiffness by region. In particular, this study identifies the significant difference in the stiffness of the DM tissue associated with the superior sagittal sinus when compared to the other DM regions. Constitutive modelling was carried out on the regional mechanical testing data for implementation in Finite Element models with improved biofidelity. This work also presents the first biochemical analysis of the collagen I and III, elastin, and fibronectin content within DM tissue by region, providing useful insights into the accompanying macro-scale biomechanical data.
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12
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Pasquesi SA, Margulies SS. Measurement and Finite Element Model Validation of Immature Porcine Brain-Skull Displacement during Rapid Sagittal Head Rotations. Front Bioeng Biotechnol 2018. [PMID: 29515995 PMCID: PMC5826385 DOI: 10.3389/fbioe.2018.00016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Computational models are valuable tools for studying tissue-level mechanisms of traumatic brain injury, but to produce more accurate estimates of tissue deformation, these models must be validated against experimental data. In this study, we present in situ measurements of brain-skull displacement in the neonatal piglet head (n = 3) at the sagittal midline during six rapid non-impact rotations (two rotations per specimen) with peak angular velocities averaging 51.7 ± 1.4 rad/s. Marks on the sagittally cut brain and skull/rigid potting surfaces were tracked, and peak values of relative brain-skull displacement were extracted and found to be significantly less than values extracted from a previous axial plane model. In a finite element model of the sagittally transected neonatal porcine head, the brain-skull boundary condition was matched to the measured physical experiment data. Despite smaller sagittal plane displacements at the brain-skull boundary, the corresponding finite element boundary condition optimized for sagittal plane rotations is far less stiff than its axial counterpart, likely due to the prominent role of the boundary geometry in restricting interface movement. Finally, bridging veins were included in the finite element model. Varying the bridging vein mechanical behavior over a previously reported range had no influence on the brain-skull boundary displacements. This direction-specific sagittal plane boundary condition can be employed in finite element models of rapid sagittal head rotations.
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Affiliation(s)
- Stephanie A Pasquesi
- Injury Biomechanics Laboratory, Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Susan S Margulies
- Injury Biomechanics Laboratory, Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
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